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Fencer Vulns
medium 4.9

CVE-2025-2559 json

Org.keycloak/keycloak-services: jwt token cache exhaustion leading to denial of service (dos) in keycloak

published 2025-03-25 19 mo ago modified 2026-09-21 49 d ago also GHSA-2935-2wfm-hhpv , EUVD-2025-8064

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 53%
public exploits
0
none known

Summary

A flaw was found in Keycloak. When the configuration uses JWT tokens for authentication, the tokens are cached until expiration. If a client uses JWT tokens with an excessively long expiration time, for example, 24 or 48 hours, the cache can grow indefinitely, leading to an OutOfMemoryError. This issue could result in a denial of service condition, preventing legitimate users from accessing the system.

Patch / fix

  • Red Hat Red Hat build of Keycloak 26.0 26.0-12, 26.0-13, 26.0.11-2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-2559 updated cvss 4.9

org.keycloak/keycloak-services: JWT Token Cache Exhaustion Leading to Denial of Service (DoS) in Keycloak

  • Red Hat Single Sign-On 7 keycloak-services
    affected: no fix available “Fix deferred”
  • Red Hat Build of Keycloak
    fixed: vendor fix RHSA-2025:4336
  • Red Hat build of Keycloak 26.0 rhbk/keycloak-rhel9 26.0-1745967474, rhbk/keycloak-operator-bundle 26.0.11-2, rhbk/keycloak-rhel9-operator 26.0-1745967472
    fixed: vendor fix RHSA-2025:4335

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.70% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<=26.1.4
 no fix listed

Affected products

  • Red Hat Red Hat Build of Keycloak
  • Red Hat Red Hat build of Keycloak 26.0
  • Red Hat Red Hat Single Sign-On 7

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.